The SS 1.2 is a nice lift, but it's almost double the price of the OME kit and comes with a bunch of expensive custom doodads that you can either make yourself or they just plain aren't needed, like:
-The brake line extension (you can bend the bracket down for free)
-The sway bar adjustment brackets (you will want to remove the sway bars anyways if what you want is flex)
-The flush zerk fitting (buy a small M6 bolt for $1 or a needle grease zerk fitting)
-The adjustable pan hard bar (buy a pan hard drop bracket from Toytec and save $150 or just keep using the stock one and let the axle be 3/16" off to the passenger side) I have my stock pan hard and have had no problems for several years now.
-The Daystar bump stops (if you want more flex, these limit it). I have much more flex than a SS 1.2 will give you and I still rest on my factory bump stops, no problem.
-Parking brake bracket (never needed one for mine).
The SS 1.2 lift can be sourced and pieced together with what you actually need for ~1/4-1/2 of the price SS gets.
I love my OMEs and they are much better for carrying extra weight (from bumpers, sliders, skids, etc..) than the Tundra/LC coils, but the Tundra/LC coils ride smoother so that's a personal choice. My OMEs ride as smooth as any kit out there, but I also carry ~600 lbs extra weight so that makes them ride like a Caddy.
The only issue I have with the OME kit is, if you remove your rear sway bar, the rear shocks aren't long enough to let the suspension do a full cycle so you will bend or break the shocks after a while. I got Tokico Trekkmasters made for a FJZ80 Landcruiser (for $35 each new) and they are ~2" longer than the OMEs and support all the flex you will be able to get.
Since you mentioned flex, some custom rear heim-jointed lower control arms will give you more flex than anything else will. Here's some pics of my flex:
And the thread for my links:
4runner Custom Lower Links ! - Toyota - 4Runner . org Forum
Here's a good read all about your lift options:
3rd Gen 4Runner Lift Information and FAQ's - Toyota - 4Runner . org Forum
Good luck!