Before you make your choice, you should take into consideration how much cash you have to spend on your skills anyways. Summoning is rather expensive, and so if you don't have much cash then it might be smart to use the lamps to get to 93 sum do you can do slayer manually and make cash along the way. If you have lots of cash at your disposal and you are more concerned with the amount of time it takes to complete things, then you should put the EXP into slayer in order to save you many hours of mind numbing tasks.
Also, what is the best way to turn your effigies into Dragonkin lamps? I know this does not apply to you because you are already maxed in all skills, but I have never used one yet myself and don't know much about them. When I did some reading on rune wiki it said you can get players to assist you with the required skills, and I noticed whenever I am dungeoneering on W117 there is a ton of people near the bank who sell skill assists. Do you just take all your lamps there and find people to assist for free? or is there a better place to go such as a CC that offers free assists? I have maybe 9 or 10 effigies in the bank and after reading about Dragonkin lamps I am interested in using them.