I have just come out of a similar experience for my 50th, a desire to own a great instrument that will age with you. Like yourself I narrowed it down before asking the bass community. I was between and ACG a WAL or an Overwater.
The whole experience was fantastic and I encourage you to enjoy it; every little decision is your alone. I opted for an ACG in the end, I loved the whole process, Alan was great, as I’m sure each of all the UK makers would be. I just love the ACG preamp, I’m not a professional musician so I understand the difficulty in investing 3-4k in an instrument, on the other hand, what a fantastic position to be in!