Hello,
Thanks for additional info. Yes, it makes sense to enable LAG between Your SRX and Your switch for better LB on this hop only.
However, vlan 100 & 101 will be seen on SRX side as 2 separate logical subinterfaces, and in this case I'd recommend to use option [2] in my previous post since ISP link redundancy is really 1:1 in this scenario, not 2:1 as Your OP implies.
In simple words - if Your ISP1 link fails, You only have 1 choice remaining - that is, ISP2 link - irrespective of how many VLANs You may have configured on ISP1 link.
HTH
Thx
Alex