Lived without a DW for 46 years, and was perfectly happy not to have one. Then we moved into this house, which came with a crappy old DW. We didn't use it much, except for holiday dinners and get togethers. Got a new one about 8 years ago, and I'm a convert. No more piles of dirty dishes in the sink or on the counter. We are down to just Mr. SP and myself now, so only run it twice a week. Still worth it. Also, anecdotally, we seem to not share our colds and other bugs as much. When one of us is sick, I can put the DW on 'sterilize' and nuke those germs. We did buy extra cutlery - with only running it twice a week, we always seemed to be out of spoons and knives.
We have a GE - nothing all that expensive or fancy, but does the job and is reasonably quiet and energy star rated. No problem installing it - if it's set up correctly, they slide in and out easily. Ours is secured to the countertop with one easily accessible screw at the front. I would not buy Frigidaire - friends did, and it was a nightmare of leaking and horrible customer service from day one. The front panel was visibly warped, and it still took 3 months to get a refund and replacement, even after the service techs said it was not repairable.