It really does depend on your whole team, but Roost is better in most cases.
- Just exactly what Spooky Terrain pointed out, any Dragonite wouldn't want to go Extreme Speed with Tapu Lele, as its Psychic Terrain blocks and negates any priority. In a HO, longevity isn't as important for offensive Pokemon, so Dragonite can pick up Extreme Speed to revenge kill weakened threats, like Weavile (that has Ice Shard).
- With the addition of Heavy Duty Boots, Dragonite can switch into Stealth Rock and have its own Multiscale still active. So, Dragonite really appreciates Roost which can restore back to full HP and halve down any damage with Multiscale.
- As for Extreme Speed, there's no reason to use it if it's a defensive cleric Dragonite with Heal Bell, Defog, etc. Roost is a must, so Extreme Speed isn't easy to fit at all. However, in a hyper offensive team, Extreme Speed provides with the highest priority move available, so revenge-killing is appreciated. For example, Weavile can do solid damage to Dragonite, even with Ice Shard if Multiscale is down. Extreme Speed can avoid that circumstance, as it outspeeds Ice Shard and can OHKO Weavile after a single Dragon Dance and Stealth Rock damage.
tl;dr, it depends a lot on your team, but with the current one I'd suggest this moveset:
Dragonite @ Weakness Policy / Heavy-Duty Boots
EVs: 252 Atk / 4 SpD / 252 Spe
- Dragon Dance
- Dual Wingbeat / Ice Punch
This set is quite a lot different from yours, but that's because Dragon Claw and Brick Break are unnecessary. Earthquake + Ice Punch already forms the infamous BoltBeam combo, which has a wide coverage. Dragon Claw doesn't cover anything, so it's not a much needed STAB as Dual Wingbeat.
Heavy-Duty Boots allow it to switch into Stealth Rock keeping Multiscale, though if you run Defog on Lugia then Weakness Policy can be used too.
Hope this helps!