Welcome new member.  It's a complex question.  The current V6 motor itself is fine.  Good power, reasonably reliable.  The problem is the 8-speed transmission it comes with (or specifically the torque converter), which has been a sore spot. If you get one, I would baby it and absolutely not tow anything if you can.

The new truck will certainly be a step up in fit-and-finish; it looks pretty nice.  And I believe they are putting a different transmission in it; could have problems, too, but I doubt it will be any worse.  But the new engine and all the tuning variations are a wild card.  (It is an interesting/weird strategy.  They are going to put the same basic engine in all trim levels, but give it different tunes for different power levels depending on what trim level you buy.)  So the transmission will likely be better, but the engine... who knows, might be worse.  

So I guess the answer is the new one will probably be better - better fuel economy, more comfortable/nicer, more torque and better transmission for towing, maybe more reliable overall - but keep a close eye on the engine.  If you can wait 6-12 months to see if any problems come up, I would.

[By the way, the better current option is the I4 diesel with the 6 speed.  But they never made many of those and they are really hard to find.  People who have them like them, and would be very good for light towing and long commutes.  Even better, if you can work out the budget, is the Silverado/Sierra with the 3L Duramax (LZ0) engine; more reliable than any of them, better for towing, and better fuel economy; inventories are rising right now so you might be able to find one at a discount.]