Since we all had the good sense to choose the same distribution, I feel I can trust you all to give me some advice about hard drive choice.

I am looking to upgrade my 4TB Raid5 (consisting of 1TB hard drives) with 3TB hard drives. I'm not sure yet what raid I'm going to use, but I could use advice on drive manufacturer.

I have multiple Seagate drives in use now, but given the recent news regarding 3TB Seagate drives I'm unsure which way to go. Any advice would be greatly appreciated!

Hard drives are really hit and miss in terms of reliability.
I always research based on model rather than manufacturer.
In the past I've used newegg's reviews on a per-model basis to help my decision.
Go to newegg and filter for best rating in that capacity range.
I bet you'll see some good reviews for Western Digital. I heard they're good this year....
For lower-capacity laptop drives, I tend to prefer Fujitsu, then WD.
Another guidepost I've used is to find out what models big companies like Dell and Apple use
for their higher-end machines.

Every WD Digital drive that I've had that wasn't a green has been excellent.

Agree with both statements above. But I have always had good luck with WD enterprise and black drives, but not green like Dugan said.

I've had a WD Green series drive running well for 4 years now with no issues.

Drives vary but generally Western Digital are always reliable.

I've had consistently good experiences with Western Digital.

I've also had no problems with Seagate, but I've not purchased a new one in five years or so.

I've had two Seagates fail on me when still quite new.

My WD Greens have been holding up well... I've only replaced (upgraded) them when their capacity isn't enough for me anymore. However, they are just individual drives on my system (used solely as storage where speed is not necessary) and are not part of any redundancy setup. I do use a Crucial SSD for my primary partitions.

That being said, with a system that is using redundancy (raid, jbod, btrfs, etc), you don't want Green drives. Personally, I've never had a Western Digital fail on me short of when the post office pretty much destroyed a computer I shipped... but the drive still managed to hold out long enough for me to retrieve the data on it. I know this is just anecdotal, and there's someone out there who has only had problems with Western Digital, but, they'll be the drive for me unless something serious changes. If you go with WD, I would suggest using their red series, as that is the series designed for use in RAID-type setups.

If you can afford it, get the Velociraptor series.

At that price ($429/1TB), you might as well go for the more cost-effective ($327/1TB), and faster/quieter, solid state drive (SSD).

But slacker1337 wanted to move away from 1TB drives to 3TB drives, so since velociraptors max out at 1TB, they wouldn't work out anyway...

I've had varying luck with all manufacturers, I don't pay much attention to them but to the model lines. Here's another aspect, you are using these in a raid, is this a 24/7 uptime? If so, look at the NAS drives, they spin slower saving energy and run cooler.

I've had a good experience with WD Red 3TB drives in a similar situation.

I'm still not sold on SSD drives. I know the problems with SSDs are few, mostly revolving around setup and the fact data cell degradation is not as bad as it used to be, but that's too many issues for me. HDDs fail, but the failure rate versus SSDs is unmatched.

I haven't checked out the Red series yet but mostly Red is for NAS setups, not workstations. Doubt I'll ever get one.

Black editions are for Gaming and High Performance setups. Have two, love them. They serves as my main system drives for Windows Server 2012 R2 and Slackware 14.2.

Blue is performance and general daily use. Mostly used in replacements of system drives. I go through these like water.

Green is for low power, low heat, and long term storage setups. I have one serving as my data drive mounted to /home and C:\users with an NTFS partition.

VelociRaptors are for just raw speed and ultra high performance (yes they are limited to 1GB but they are 10,000rpm drives while Reds, Blues, Black, and Greens are limited to a max of 7,200rpm but have higher capacity). Don't have any yet.

Since you didn't mention type of service, concerns (performance and/or reliability) or cost factors I'd like to ask if this is either Enterprise use or in any way "mission critical"? Although Serial SCSI rarely comes with the commonplace 5 year warranty that Parallel SCSI used to have, they are still built more ruggedly both mechanically and electrically as well as having choices of extreme ruggedness (usually slower spindle speeds) or extreme performance (10K - 15K RPM drives are common) and SATA drives are 100 times more likely to encounter bit errors. The cost per TB is higher but 3TB SAS drives can be had for under $300 US with substantially higher performance and longevity over SATA.

Most everything I have read in the past few years (quotes from two such articles are below) show SSDs are either about the same or slightly more reliable than HDDs. Failures were common when they first came out, but they've really improved over the years, which is why many datacenters are replacing HDDs with SDDs.

But for "raw speed and ultra high performance", you're still limiting yourself to the seek time of the drive. SSDs will surpass the performance of VelociRaptors for less price. Unfortunately, while the VelociRaptors are nearing the pinnacle of consumer HDD performance, they are easily surpassed by many quality SSDs.

But suggesting VelociRaptors doesn't fit the OP's request. There was no request on the speed of the drives, just capacity and quality.