We tow a really nice Shasta 18ft bunkhouse with a half ton truck. Ours was $11k new, so it is well under your budget. They do make larger models and seem comparable in price to the brands you have mentioned.
Shasta seems well made and has some nice quality flooring & windows. Tank capacity is fairly large in comparison to other 18ft. models. Full specs are in my profile.
We started camping with a very bare-bones featured travel trailer, so there are little things on our new Shasta that seem luxurious in comparison.
Some features to look for that we like -
The electric awning. Manually unrolling/retracting it was ok on our previous TT, but pushing a button to retract the awning when the skies darken for an unexpected rainstorm is a nice piece-of-mind feature.
The next feature I like in comparison is the electric water heater - push a switch and it is lit. No more sitting outside in the rain trying to manually light the water heater.
Another small feature we found we like is the exterior lighting. We often leave after work to go camping and unhook in the dark. The light on the front of the TT above the stone guard that shines on the tongue was an unexpected nicety. The amber patio light can be turned on/off inside and it is nice for a quick look around after dark.
Our Shasta has four manual stabilizer jacks, but a Camco jack socket and the cordless drill we always bring in the toolkit makes short work of raising or lowering the jacks.
We opted for no slides for a few reasons. It is one more thing to go wrong as per above poster. We wanted something "road friendly" that we could hop inside and use at a rest stop, or overnight at a Cracker Barrel type stop that would have plenty of room to move around in without needing to extend slides. No slides was a good choice for the two of us. Since you are four people, I respect that you feel you need slides, though.
-Laura
2016 Shasta Oasis 18BH (specs and floor plan in profile)
2015 Ram 1500 Hemi