I like playing FedSuns vs. Combine Dark Age fights in MegaMek with some regularity, so I do have some appreciation for the ReLasers. I don't need them everywhere, but its nice to have some of them to focus on the hardened armor units. I can ususally deal with FerroLam, Ballistic Reinforced, and Reflective without ReLasers, but they are my preferred counter to Hardened.
Since my beloved Gunsmith carries medium X-Pulses exclusively, I am contractually required to like them...although I don't generally consider them to be better or worse than standard IS pulses, just different. If you have an already cool-running mech and want to slap some pulse lasers on, why not take the extra range? If you have cooling problems, it's usually better to use standard pulses or non-pule lasers. The best thing I can say about X-Pulses is that they don't require remembering any new rules that regular pulse lasers don't have. All the differences are on the record sheet.
VSP's...Meh. If I was building a custom design I'm not sure I would ever choose VSP's, but I've never shied away from using a unit that had them. They aren't bad, just heavy. On mechs, I just need enough armor to survive getting in close and applying consistent, repeated damage. I don't really like them on glass-jaw units because their whole deal is doing consistent damage at close range, so they need to survive as many turns as possible to get their BV's worth out of them. Also, Large VSP's can be pretty nice on larger Aerospace units that have lots of tonnage to throw away like dropships and heavy fighters.