title says it all.

I am soon receiving my X/Rt valve and I want to get into HPA without any problems with a tank that best suits basic mags. So what should I want? I am looking for the ability to sweet spot as easily as possible. I do not have the ability to for an intelli even though i wish I could and sweet spotting/RTing is my only hope to get a eye catching BPS. So what should I want.
2 things that would also best suit me.
1. The larger the size the better.
2.45k is best (obviously).
All help is widely appreciated and thanks in advance.