Unfortunately having radiators on the VRM is not very reassuring. If anything it could mean that the power phases are less efficient.
10400F / H410 m.2 236 euro
1600 / B450M 205 euro
Not worth saving 30 euro with the ryzen. 10400f is 20% faster and less stuttery. H410 could support the upcoming Rocket lake.
H410 is limited
Only 2x DIMM slots
Unless you pay a similar price many of the affordable options have no M.2 slot majority that do offer an M.2 slot only offer 1. The B450M Pro 4 offers 2x M.2 slots and 4x DIMM slots.
Limited upgrade path. The B450M will support Ryzen 4000 series. H410 well we will have to see Intel likes to force mobo upgrades.
Ryzen 1600 AF if you get lucky Silicon lottery wise you may be able to push up to 4200 MHz considering its a Ryzen 2600 by a different name and the 2600X boosts to 4.2 GHz this is a decent possibility something the 10400F doesnt have at those clock speeds performance difference wouldn't be noticeable to the average user. So you give up storage / I/O options for a small benefit in regards to performance that due to the GPU selected you would never actually see. Example In something like Assassin's Creed Odyssey where the Intel chip wins by more than 10% its getting 95+ FPS vs the AMD chip at stock getting 85 or so FPS. A 1660 Super only gets 50 or SO FPS when using the same settings. Meaning your GPU limited not CPU limited.
If your going to go with a comparable 10400 system with the same capabilities you can afford a Ryzen 3600 and when looking at the entire work load its +/- 5% with a still better upgrade path moving forwards do to their outselling Intel in the DIY market in the etail space. Meaning getting a cheaper higher core count CPU will be a bit easier than the Intel options which tend to retain a price premium.
Going with a 3600 based build would work out to around 840 bucks. The 10400(F) based build with equal capabilities comes to $840. So its a wash and both are equal.
Still the 10400 is a valid option but not at $700-750 while getting the same level of I/O, memory, and storage options vs a 1600 AF.
Then there is the H410 supporting Rocket-Lake argument, we know for a fact AMD will support Ryzen 4000 on B450, Intel side, who knows they tend to like to force motherboard upgrades so I find it unlikely. If it is a drop in upgrade its likely more a refresh than a new design more often than not. AMD has also managed to increase clock speeds on their current 3000 lineup if the next gen CPUs hold the same clocks and gain again in IPC its possible a user on B450 can opt for a an upgrade path that doesn't require a possible mobo swap and gets more cores for there dollar and equal or better performance while Intel continues to fight their node issues. There is also the possibility of the used market and considering AMD is selling more CPUs in the DIY market means acquiring a cheaper used Ryzen processor down the road is an easier task.
That said, again 10400 is a valid option. I just can't see using the cheapest possible motherboard to make it fit the scenario. Even if Rocket-lake does support H410, would you opt to put a power hungry 8 or 10 core CPU that can suck down 250-300-watts at stock under heavy load on an H410 board? Or take the more power efficient AMD option down the road in say a 3900X or equivalent that peaks at 145-watts give or take? Realistically speaking that B450M board will have an easier time with a stock 3900X or any other AMD cpu than that H410 will with Intel's current lineup. So looking at longevity and upgrade path. I opted for the safer upgrade route.
All of this is taken into account within reason. Obviously can't make everyone happy but I am glad to see some good discussion come from it
As for powersupply I used the 450 BT and it works really well. I also put it in another budgetsystem I build with i5 8400\RX 480 and it works very well there too so I can recommend that.