A drill would be better if you can find one which works at the speeds the spindle runs at (most are made for low hundreds of RPM) — there are specialty drill-mills which are made for high-speed spindles, but they’re pricey — I believe Harvey has one.
A couple things I would add in general though. At this size the most important thing is going to be runout. Old rule of thumb is 10% of the diameter of the tool will break a cutter. This was mainly applied to milling but has the same or worse implication for drilling. Drills REALLY don’t like side load and any runout will functionally be a feed.
At this size this really isn’t that much of a concern. Even at 100SFM this size drill would be good up to 32KRPM. Bigger issue is plunging it reliably and fast enough for the material.
Both of those are pretty similar with AlMg1 (5005) being easier to machine. Both want high feeds and the higher the temper the better as the machinability goes up (for these alloys). In the case of either you are probably going to have to have a cutting fluid. Normally I’d recommend an oil based one but for this I’d say get the thinnest one you can as actually getting the fluid into the cut is going to be much more important than anything else. I’d also limit my cutting depth to the 0.5mm you indicated you could go to.
One last thing I’d look at is limiting the length of cut on the drills you get. The shorter it is still being able to clear your hole the better. If you can find them, medical / needle drills will buy you some more forgiveness. They have much more core material and usually have shorter cutting lengths than PCB drills.
Hope that’s helpful. If there’s anything I can expand on or help with let me know.