TOTO UltraMax vs drake

I am enjoying your forum and comments on these two toliets. I am looking to replace our 18 yr old american standard.
The problem is from day 1 this toliet was slow to flush but not real problem. Now when I flush the level wants to rise before it finally flushes(makes me nervous).
Also the standing water level changes depending on whether the washing machine in the next room is draining??
We may have a venting problem? and although we are on municiple water, our water pressure at times drops to 22 psi.

Now for the ? Could I get the TOTO UltraMax MS854114 S (power flush) vs MS854114 (gravity flush) vs TOTO Drake CST744S
I think I read somewhere that the power flush requires at least 25 psi. Would this solve our problem or do I need to call a detective/plumber.

To add to my problem...hubby is no help...an accountant and a Colts fan. Great guy, but knows nothing about plumbing and you know where he will be on Sunday while I am out shopping for toliets.
Thanks for your help,
The wife

The Drake and the Ultramax have the G-Max gravity flush.
Very similar in performance.

The Ultimate is like the Ultramax, but not quite the kick in the flush.
It still works very well for home use.

All three use a 3" flapper in the tank.

Really, any would be a good choice.

If the bowl on the old one is draining different than it did previously, it sounds like you may have a partial clog in the drain line.