I've used Avis and Enterprise on a regular basis, quite ok.
I've also used Mr rent-a-car quite a bit, they are Rmd.
No issues like you mentioned before.
taking pictures is good, most standard routing check (all rental car company staff will do this for you) is to walk around the car once before you sign the "release" form, noting scratches, etc. mechanical issues is not your problem at all (esp. big rental car companies), for they are the ones that should have checked and top up all the fluids, etc. before customers rent them.
The only thing that typically needs checking (they seldom check) is tire pressures. Usually low.
Fueling up is fine also (cheaper than you return the car and have them fuel up for you).
If I'm not mistaken, cost of car rentals pretty much boils down to the type of vehicles (subcompact, vans, etc.) pricing availability and package deals.
I once quoted for a 7 seat passenger van (nothing fancy, just caravan and it's equivalent) here in Vancouver. 1 week costs close to 1800CAD rental.
On the lighter note: Accent or echo weekly deal works out to about 48CAD + amenities per day (on a weekly rental package).
So, do some online shopping before you approach car rental company counter.
I got the Ford Fusion for $400Cdn (8 days) , in LA. I guess not too bad deal...
But we accidentally drive into a toll road...not sure what's the charge ...