So I am looking at these three mostly. For starters I don't live in the country, but in the burbs. I do have a family place to go to in the country that I would take it with me to clear brush, small trees etc, mostly for trimming around ponds and deer shooting lanes.

I'd like something that is light that I can handle all day that has sufficient oomph to cut the above. I am not a logger and am not building a log cabin by myself.

Any suggestions?

Go for bigger than you think you need you will be pleased.

I'd go with an 18 " bar.

I have an Echo and love it. Starts with ease and runs like a top. Great saw.

From reading old OB threads and also other places it sounds like stihl, husq, or echo are the way to go...

Stihl....end of story. As a previous poster stated, go a little bigger than you think. I have a MS 390 with a 20" bar. Of course, I cut down big oaks (firewood) and pines (because we have too many) on our property.

Definitely go bigger than you think. I have three stihl's and I wouldn't use anything else.

I'd recommend the Stihl MS290 Farm Boss 20". If you go with a smaller engine, get at least an 18" bar. The 290 might be to big for you, but you'll find out that if you have a big saw, then you will use it for bigger jobs. Since you have land, you probably have alot of dead trees(if you in Texas), and the bigger saw will come in handy. Good Luck.

From lots of experience at trimming brush and limbs, get the longest bar whatever saw you choose can handle. It saves your back from having to work bent over while you limb branches all day.

I'm gonna go against the grain here and recommend one of the three you're actually looking at.
For your stated purposes I'd get the 170 with a 14" bar or the 250 with a 16" bar. I have the 250 with a 16" bar.
FWIW, dad has a 280 with a 20" bar and a 170 (or 180, can't remember) with a 14" bar and he uses the small one much more.

I've looked at Stihl a bit and I'm getting one in a month or two. I can't recall the number now but I'm going with one in the professional line with a 20" bar. Go big or go home. I have 20 acres of woods though with drought killed trees.