Help me pick a new tire and size.

New 2015 Rancher 4×4. Its the base model with none of the fancy bells and whistles, and solid rear axle.

The factory tire sizes are as follows:
Front Tires: 24 x 8-12
Rear Tires: 24 x 10-11

The 4 wheeler is about 5 months old at this point and only has about 320 miles on it. I do not plan to upgrade the tires immediately but want to get an idea of what Ill be looking for in the somewhat near future.

I am an average rider – 90% of my riding is on dirt roads (sometimes pretty sandy ones), small trails, and open pastures. I will not be mud bogging or driving through lots of water, except when it is unavoidable. I want a good all terrain tire geared toward maximum traction and overall dependability.

In terms of size I had been looking to step up to a 25" tire from the 24" stock. It just seems that 25" is a much more popular tire size. I had not planned to go bigger than 25" because I understand you lose power by doing so. If there was no power sacrifice I wouldn’t mind a 26 or maybe 27 max, but I do not want to sacrifice ANY power. Would there be any loss of power going from a 24 to a 25? What size would you expect to see a loss of power? If going to 25 would be any loss of power I will stick with 24, I just wanted to get into a more popular size with more options, plus the 25 would bulk the 4 wheeler just a tad and give a tad more ground clearance. My knowledge on size vs. power loss however is very limited so im curious on this. It seems when shopping for 24’s though the options are much more limited.

In a nutshell: I want the best trail riding/ all terrain tire out there, and Id like some suggestions on what size would be ideal without ANY loss of power.

EDIT: also what about wheels? Any suggestions there would be welcome