Thetford or Barker Portable Waste Tank??

They're both good totes and you can't go wrong with either one. I have an older Barker 32 gal that comes in handy from time to time. If buying again, I would probably go with one of the 4 wheel models with side discharge. I went with the 2 wheeler mainly due to the lower cost. Be warned; they all get HEAVY when full.

We use ours only for gray water.

I prefer the Barker. It comes with pneumatic (air filled) tires. The hose is detachable making it easier to drain. It also has a detachable handle for towing.

I have Thetford 35 gallon and like it very much. I did have to drill the wheel axle (both sides) and add cotter pins between the washers to prevent the wheels from rubbing on the tank body. Bolt fell out of handle body due to hauling over rough terrain. Simple fix to add another bolt. Otherwise, I am satisfied with this tote.

Lakeside

IMO, the most important thing to think about is: "Is there a dump station here?"
Getting that thing filled up and finding there is no place to dump it would be a VERY bad situation!
That's why I sold the one I had. Any campground I was in either had full hookups or no hookups or dump station. It sat under the workbench for about 5 years gathering dust, then I sold it for $15 in a rummage sale.

I also have the Thetford. It comes with a small hose you use to hook up to rinse it out, and an indicator that tells you when it is full. Heavy duty wheels and the handle is designed to fit on your hitch ball. Tows over gravel surfaces and sand as well as speed bumps very well.

I've got the thetford and love it. Hose stays with it and tows great. Main thing is get one close to the size of your tank size so one trip does it for each tank.