First, I'd call Mosley to see if they have either one of their models "in stock for immediate shipment," like "today." If not, I'd think about something else because their delivery history is not good -- many complaints on the air and all over the internet about people waiting 2-3-4 months for delivery and never really being sure when they're going to get anything.
But, if they have it "in stock" and can ship "today," then that's another story.
The Mosley "mini" beams are very similar to the Cushcraft MA-5B which is also a "mini" beam for five bands. In fact, these products are extremely similar. One difference is that Cushcraft has many distributors and one of them is likely to have it in stock, so if I wanted one I might be able to get it tomorrow and not wait 4 months for it.
The Traffie HexBeam HX5Bi is an excellent product. I'm not sure about their delivery status, either -- and I'd recommend you check this. But the HX5Bi HexBeam, unlike the "mini" beams from Mosley or Cushcraft, has full gain on all five bands 20-17-15-12-10 meters. The mini beams from M and CC only have some gain on 10-15-20 meters and zero gain (just a rotary dipole) on 12 and 17. It makes a difference. The HexBeam definitely works better on 12 and 17, has a front-to-back ratio and gain.
The HexBeam is also small, lightweight, easy to build, low wind loading and requires absolutely no adjustments.
If it were my choice I'd go for the HexBeam; however, again, I'd check delivery for that one also because I'm not the type to order and wait.