I've played mozart sonata k.310, chopin prelude no.16 and learning the Rach moment musical no.4. Now I'm trying to get started on beethoven sonatas. Which one should I play?

I suppose you'll have to play most (if not all) of them at some point, so it really depends on what you are looking for. If you want a Classical-ish sonata, maybe op. 10 no. 3 or op. 2 no. 3. Die Jagd (op. 32 no. 3) is also very popular nowadays. From the later sonatas, op. 90 is always great, and 109/110 might be easier to tackle before 111.

well there's 32 of them, and they all have their own characteristics...but I don't think I'd start with op 54--it's really not the best in my opinion, and just doesn't sound all that good, especially compared to the two great sonatas on either side of it chronologically (waldstein and appasionata).

there's multiple other threads here about the relative difficulties of the various sonatas.  use the search button (between help and profile immediately above "piano board."

  I suggest you start with one of the "easier" ones such as op 14 or 49, and then branch out to some of the well-known sonatas such as the Pathetique (op 13), Moonlight (27 #2), or the Pastoral (op 28).

I do like 31 #3...that's one that could certainly use more exposure.

oh yeah, google "schiff guardian uk." 

I know there will be people that disagrees with me but, op14 no1 1st movement isnt as easy as everyone says it is, ive mastered it and it needs so much colour and texture, also it is very unpianistic, as though beethoven was meant to write it for the string quartet

Don't start off with waldstein or appassionata...

There are some which are really fun to learn and play among his earlier ones. Yes, people usually do start of with op.14 or 49...

If you want something harder, any of these: op.2 no.1/2 op.10 no.1/2

the 4th mvt of op.2 no.2 is not easy. Op.2 no.3 is quite challenging, same for op.10 no.3....i definately enjoyed learning those alot though

You know, there are actually 35 piano sonatas of Beethoven. For a change, you could try one of the three WoO piano sonatas. (I think they're not quite as difficult as most of his other piano sonatas, too.) The score may be harder to find, but Barry Cooper's new edition has all 35! Cooper's edition is the best for Beethoven, I think.

I'd go for the shorter(but still quite challenging sonatas):
op.54, 78 and 90

Those are wonderful pieces. However, I think for someone's FIRST Beethoven sonata, it should be an early one. That's how many people start with Beethoven's sonatas.

Original post: Good luck with a Beethoven sonata! They are difficult, but very rewarding (and fun to play)!

Go for the 'Hammerklavier' first (Op 106). It's a piece of cake!
Seriously, I'd go for A few of the earlier ones - Op 2 no 1, Op 10 No 1 or either of the Op14 Sonatas

If you want to get into any of the 'late' Sonatas, start with Op110

Good luck!!!