I subscribe to both sites. Both are EXCELLENT!
I love tennisplayer for the HUGE library of pro clips. Great stuff! The articles are excellent as well. It is a tremendous tennis resource.
I would suggest hitechtennis over tennisplayer because hitech is THAT good. The videos are AWESOME!
The instruction (all by one guy) is nothing short of
brilliant. You can also send him video of your strokes and he will analyze it and compare it to a pro. It's really an amazing deal. I also like how he will suggest other good tennis resources (like tennisplayer or tennis guru's DVDs). He does an amazing job of showing the intricacies of professional strokes, from the takeback to the followthough. The site is extremely well organized as well. You will learn how pros hit the ball with that loud "pop" sound, the secret of suprination, and so much more. I could go on forever. It's a great site!
I would seriously consider joining both, because hitech is such a good deal (VERY inexpensive for the amazing insights you will get).