I want to buy a tablet, I need more apps, free of charge, apple iPad look like more popular, is it better than android?

there is no "better", on a Linux forum, surely you know that already? I like my Nexus 7. It's ace. Other people prefer paying twice as much for an equivalent iPad.

I need GPS, sending sms.
ipad is more expensive, memory can't be expanded by microSD.
But its screen resolution is better.

High-end Samsung or Asus Android, definitely!

It all comes down to personal preference because all these tablets do the same thing at the end of the day. I am geared toward the Android tablets because of the memory card expandability, linux background, and variety of free software. Ipads are cool too don't get me wrong, recently I gave one as a xmas present to my mother in law and she loves it, but they are a little too much proprietary for my liking.

The uses you want are pretty standard and can be accomplished by the majority if not all of the tablet market.

I am probably going to by the Samsung Galaxy Note or the Transformer, at the same time it's very early in the year and a ton of new products will be released so it may be in any ones best interest to wait.

Happy Shopping

Just figure that you're going to spend "a few hundred (US) dollars" on a piece of equipment that will have no more than two years' useful service-life before it is declared "utterly obsolete" and relegated to the same digital dung-heap now occupied by the last three phones you bought. With that principle firmly in mind, buy the piece of equipment that, all things considered, will serve your present need most-completely, today. In 720 day's time, figure that you won't even be able to give the thing away in a donations-box.

If you buy an Android device, you can be pretty sure that the device will still be able to do what it's doing now, which is a lot more than you can say for Apple gear. I bought two iPhones before finally seeing the light, whereas my wife is still happily using an Android phone she'd bought a year earlier. Not only do both of the (non-replaceable) iPhone batteries no longer hold a charge, but you can't get software for them even if you tried.

I'm writing this quite happily on my battle-axe MacBook Pro (one of a long line of such devices), so please don't imagine that I am "Apple bashing," nor saying that what sort of equipment you ought to select. I'm just saying that you should not expect any investment in pad-technology today to have more than a two-year service life.

"Popularity," by the way, is entirely manufactured and therefore quite worthless as a basis of comparison. You are not a Lemming.

I've a first generation iPad that's still working. I use it now and again, but tend to prefer my netbook due to it having a real keyboard.
From what I can gather the "apps" tend to cost more for Apple, though I've mainly been looking at SSH, VLC, VNC remote controls and MPD remote controls -- other apps may be the same. I have found free ones for iOS, by the way, but they're adware and crippled compared to the Android ones. There seem to be some other cool Android apps that never make it to iOS also.
I also struggle to use an iPad without iTunes as there's no other sensible way to get files on and off it. Having to email yourself is a bit pathetic for such expensive kit.
The above means the iPad only gets used for reading on the toilet, reading Twitter (for which linux has no decent "apps" I can find) and playing a silly game. In the few weeks I owned a rubbish old Sony/Erikson Android phone I could already find more use for it than the flash iPad.

128GB, 3G ipad cost 950 USD in malaysia, pretty expensive.
While a Samsung Galaxy note tablet with 32GB and 3G, cost 700 USD here.

ipad 4 has mush better sreen resolution

I bought Acer iconia 701, 32GB, can expand memory, can SMS but cannot call.
Full HD screen.
Android Jellybean.

I have the Samsung GT2 7.0 with 8gb and can expand up to 32gb sdcard. It came with ICS but has been updated to Jelly Bean since January. The display is not as good as the N7 but it has been serving my purpose since August quite well.

I would recommend a Nexus 7. Not only you get the latest android updates from Google, you also get a great product for the price. I have a Nexus 10 but it seems Nexus 7 is not only small enough to carry around and hold it with one hand but also serves most other purposes.

Android tablet, specifically Nexus 7 3G, but you will have to use skype as there isn't a messaging app to my knowledge.

Nexus 10 has even better screen resolution. Nexus 10 got 300 ppi while ipad 4 has got 264 ppi.

But Nexus 10 has no 3G/cellular ability.
Only wifi. It also cannot expand memory.