Linears are not my favorite type of switch. However, if you are interested in Cherry mx or clones, Cherry started out with a purely linear switch (mx black), and this is still what they do best.
Vintage blacks are legendary for their smoothness, but some folks find them too heavy.
In the "vintage" category, there are linear Alps switches, such as the SKCC Greens found in the IBM "Pingmaster" boards and SKCL Yellow or Green switches found in, for example, some older Zenith boards.
Contemporary Cherry mx switches tend to feel scratchy, but Gaterons tend to be smoother. Among Gaterons, I like their Yellow switches. Gateron Yellows are very smooth and the weight is ideal -- heavier than Cherry mx Red and lighter than Cherry mx Black.
I haven't tried Zeal linear switches, but I like their tactile switches -- I've tried Purple Zealios (65g) and Blue Zilents (67g). Note that the spring weights of Zeal switches refer to the bottom-out force rather than the actuation force. I find the Zilent 67g switches to be a bit light. In fact, I replaced the spring on the spacebar switch with a heavier spring because I was causing too many unwanted spaces.