Coming from a family that went to a lot of downhill races – with a brother who was sponsored and competitive in the Junior and Youth cats – you will destroy rims on a fairly regular basis when racing competitively. They become wear items like tyres.
Learn to rebuild wheels, get a few spare rims and be prepared to rebuild your wheels every so often. Pro 4 hubs would be a good start as the hubs are great quality and suited to long term use with lots of different rims.
Whilst there is some variability in rim strength between manufacturers, it’s generally a function of width vs weight. The heavier the rim, the more durable it will be and less competitive the bike will be.