Brand-names are different up here in Canada, but an aluminum 5x10 single-axle is the ideal size for our (small) Mule MX Pro. For a larger UTV, or with front blade, a 6x12 would be better.
There are 2 schools of thought. Go big (14'++, steel, heavy) for flexibility and convenience; or small for weight and maneouvrability.
We've chosen the latter, so that we can tow it with an SUV rather than a truck, and so we can go down windier roads and turn around in tighter spaces. If you live in wide-open spaces, or never drive anything smaller than a 1/2-ton anyway, that's all less important.
Lightweight single-axle trailers often come without a front (tongue) jack. Do yourself a favour and get one, even if it's the cheapest available bolt-on.
With our 5x10, it can be hard to get a good angle on ratchet straps at the corners. We find it way easier and faster to just add an extra strap at the middle of each side to stabilize than to fiddle with getting positioning and corner angles just right.