Firstly you need to check if each group has a property you will be happy with at your chosen destinations.

There are far more 'non-stay' earning opportunities and points promotions with PC than with SPG. If you go to the PC forum of FT, you will learn quite a lot about it.

SPG points are harder to earn but conversion rate is better (I think SPG is 1 to 1, PC is 6 to 1 from memory), and you get 5,000 bonus points if you transfer 20,000 in one go.

You also need to check non-points promos (e.g. "stay 3, get 1 free night" type of promo that occasionally happen) to see which one is most beneficial to you, as well as possibly look at statuses. Note that PC Gold is almost useless for upgrades although it does earn some extra points. IMO unless it's likely that you would get to SPG Plat or PC Plat, there is probably not a lot of benefits in focusing on the status too much.

I am not very familiar with HHonours, so I can't help you there, sorry.