There are several things to consider here. First how much trailer can your tow vehicle handle? Do not even look at something your rig can't handle - and don't believe the RV salesperson if they tell you it can handle the 35" mega TT you just fell in love with.
Second, what kind of sleeping arangements do you require- bunk beds? reg or queen bed? do you want a rear bed, front bed, corner bed- or no full time bed. Good sleeping arangements are imperative as that is where you will probably spend most of your time inside the RV. After all the purpose of an RV is to get you into the great outdoors - right!
Where do you plan on camping - older state and federal parks have small sites that will not hold large rigs. On the other hand, if you plan on going only to KOAs and other RV parks you should have no problems.
Do you plan on doing off season camping ie late fall and early spring? if so then you will want a rig that is well insulated, with heated tanks and large furnace - thermo pane windows would also be a good idea too.
When you find the right combination of floorplan and features - then you can start comparing brands. All RVs are hand built in batches on assembly lines so any of them can have quality problems. I don't care how many times you inspect them there are still items that slip through. The trick is finding the mfg that has the least issues and second, one who stands behind their product. Look for a mfg that offers the longest warranty.
To my knowledge, all of the brands mentioned have good quality reputations. I have owned Komforts - I had it for 13 yrs with only one problem - a clearence light started leaking after yr 12. My next rig was a Trail Lite which started leaking just after the warranty ran out - was told tuff luck by the mfg. Cost to fix was over 2K. I now have an Arctic Fox whose 2yr warranty just ran out - however I did not need it as the unit has worked fine. Northwood products have a very loyal following - visit www.afnash.com
and check out the forum.
Quality in RVs is really something you have to feel. Looks are decieving, while good fit and finish are signs of quality, it is more than skin deep. I suggest that you visit a couple of factorys if you can - seeing how they are built could be an eye opener.