legacy dcs

It doesn't work that way.  If you want to access features specific to PS-2/PS-3 you need DCS.  If you want to access features specific to Legacy you need Legacy.  Only MTH makes engines with PS-2/PS-3 built in and only Lionel makes engines with Legacy built in.

I KNOW THAT BUT WHAT IS BETTER

There is no real answer, it really depends on what engines you like and who makes them. Both have their pluses and and minuses

If you are a serious O Gauger, and stay in the hobby for awhile, eventually you'll end up with both. I like Legacy better for a few things, and I like DCS better for other things. If you have or want DCS engines, and Legacy/TMCC engines, you'll want both to access all the features of the engines.

I was going to get legacy but the shipping date dec 13 but that is last year

this is because of a manufacture issue that Lionel is trying to remedy.  there are other threads on this.  once the issue is fixed there will be plenty of Legacy systems to be had.  the CAB1L (L for light or Legacy if you prefer) are out and this will get you started. if you are in southern calif stop by the san diego model railroad museum and the san diego 3-railers and see both systems in action, (most of the time).

I have bin in the hobby for 6 years but I just got in to command control but it has bin a long wait.in April I am getting dcs and and maybe a csx genset.

I have been enjoying both DCS and Legacy for several years. Absolutely love command control, it brought me back into the hobby in a hige way. As to which is better...I have to say they both are better than the way I used to run my layout. 

neither system is "better".  Decide which features you like best and which system supports those features.  That might help you decide which system is better for you; however, as many have said why be dependent upon a particular system when you can run them all and then purchase the engine you want based upon its features and not the operating system.  In my particular case of running multiple trains on individual loops simultaneously, the DCS "ALL" command permits more configuration options (e.g. each train can consist of single or multiple engines) whereas the Legacy command permits only one engine per train if you run multiple Legacy trains simultaneously.  As a result I start three trains on one loop with DCS and the trailing 4th train is a Legacy MU.  Running Legacy as the trailing train among a group of trains (fastest to slowest) is that at the speed I run my trains (10 to 20 smph), Legacy permits a greater speed control with 3 speed steps to one MTH smph. So the long winded answer is that the best system depends upon your engines and how you run your trains.