How to route power in split-plane layout?
I'd go for number 1 because there is no chance that spikes caused by digital chips on the "red" rail can enter the analoge part of the red. BUT BUT BUT...

You need to explain what external analogue inputs there are and how they retain isolation from ANY ground local or otherwise. This could be a killer without decent differential inputs or some other form of isolation.

You also need to explain what may or may not be grounded on the circuit board and the capacitance across the transformer that creates the basic DC supply. If battery powered then no probs.