On the Branches thing, not sure I would evaluate them as a 100% bonus but at level 1-34 each branch/snow/soil is equal to 1 phoenix egg, level 35-49 each one is equal to 1 egg AND 0.1 rps when the rvr task ticks and level 50+ just the 0.1 rp per so much like eggs, they seem to have a proportionally greater benefit at lower levels (though that may be because I dont do much xping in the frontier after 35 and dont spend 2+hours in power killing frontier groups where the branches etc can roll in really fast)
As for mobs and levelling, I pretty much got into a rotation post NF of :-
1-5 whatever mobs are nearby
6-10 Lunantishees and blackthorns (same camp, one magical one plant, both mobs types drop the xp item)
10-25 ish level approriate mobs in frontiers behind the relic walls
25-35 ish level approriate mobs in frontiers beyond the relic walls usually getting to grugachs asap for giant bonus
35-39 Cathal Valley (giants reptiles insects and dragon all available)
40-44 ish Grovewoods for plant
45-50 Pretty much a mixture of fomorians in CF for giant, Botonid Dispersers in SI for insect, the reptile mobs on the north Necht beach, the trees north of the main botonid dispersers camps, big fat rencans beasts also near the botonids and trees, or a trip down to bottom of Coruscating mines where there are elemental, magical undead and demons all near the X roads at the bottom if I want 5 tasks in same area (4 mobs + dungeon) and can do humanoids on the way down for an extra task ding
Obviously EV xp groups are almost certainly the highest value xp group you can get, but with frontiers and poc in general in EU time, bleh ganked well before any decent xp is accrued and there are good high xp bonus camps beyond 35 in frontiers but there are a hardcore of stealthers/skalds/mincers/sorcs etc who patrol these so regularly that I personally gave up on them
Sort of finished with levelling on hib now so dont need these spots to be my personal faves to be mine and mine alone!!
Wyst