Fritz 14, Houdini 4, or Komodo 8 ?

Any modern engine should be more than OK. I suggest Gull 3, which is very strong, rather light on resources, and does not have many UCI settings, which would confuse a new user. It does not have tablebases support, but this is no biggie, e.g. you can use the chessx interface, which has itself online 6-men tablebases support.
Personally I am using the Stockfish devel version (which I fetch from git and compile myself) and I do not need something more for serious correspondence chess (in certain types of positions, I double check with Komodo 8, which has a different way of "thinking").
Nice post, as always.

Is it me, or does an engine sound completely pointless for players of 1300 rating (I'm one too)? I play and replay games against a free program called The Chess lv.100 and I try to spot my mistakes in my games. I have never reviewed a game and failed to spot where it went wrong. Engines play a totally different king of chess: near perfect, deep. Don't think I'll ever be able to reproduce that, so why try to emulate an engine?

Is it me, or does an engine sound completely pointless for players of 1300 rating (I'm one too)? I play and replay games against a free program called The Chess lv.100 and I try to spot my mistakes in my games. I have never reviewed a game and failed to spot where it went wrong. Engines play a totally different king of chess: near perfect, deep. Don't think I'll ever be able to reproduce that, so why try to emulate an engine?
You can learn to play like them at least in the openings. They follow the same principles we follow.
For post-mortem analysis, they can be very damaging. I have a co-worker who likes chess, and I was showing him one of my games played here, and I couldn't explain why I resigned in one of my games. I knew the position was lost because with good defense opponent had 3 passed pawns, but I couldn't show him the moves. It hasn't been the first time it's happened to me. I am usually too lazy and I almost always check with the engine. Analyse your games yourself, or you'll forget altogether the reasons behind your moves in a few weeks/months.
Honestly any engine will give you what you need until GM level...my adv,ice is if you aren't content with chess.com, get ChessBase 13.because the database is bigger and it has more options.

different level of strength in the chess engine for me is not so important, theres a lot older free version of engines that you can use in many kinds of GUIs , thats all are free, you dont need to buy a new version of engine because of its strenght, the older versions thats free to download for engines, gui interface, database, pgn, etc. are very much enough to be a very strong chess player, with the right training, study, practice with this free items i think theres no reason why not become good at chess, and one thing the best is thats all for free !

I like Stockfish 8 and you can it and a lot of other engines with the freeware Lucas Chess, which does a good job of evaluating moves.
I use it to spot oversights, but you're not going to find and engine that tells you, "You should not have attacked on the Queenside. You should have posted your Knight on the c5 outpost and stormed your d, e, and f Pawns up the middle" - and tell you WHY that was the best strategy.
You can also set Lucas to play slightly recklessly, slightly below, at, or above your strength, etc. if you want to practice a particular opening - you can tell it which specific moves you want to start the game.

I like Stockfish 8 and you can it and a lot of other engines with the freeware Lucas Chess, which does a good job of evaluating moves.
I use it to spot oversights, but you're not going to find and engine that tells you, "You should not have attacked on the Queenside. You should have posted your Knight on the c5 outpost and stormed your d, e, and f Pawns up the middle" - and tell you WHY that was the best strategy.
You can also set Lucas to play slightly recklessly, slightly below, at, or above your strength, etc. if you want to practice a particular opening - you can tell it which specific moves you want to start the game.
Stockfish 6 is released, The Strongest.
http://www.computerchess.org.uk/ccrl/404/
Still no SF6 in 40/40.
till now, they gave 87 games to SF 6, in 40/40,
http://www.computerchess.org.uk/ccrl/4040/rating_list_all.html