For an NFL RB, NYJ's offer was FAR superior to PIT's. Let's talk about the guarantees, since that's what really matters to a 27-year-old running back:
The 2018 franchise tag would have been $14.5M, all guaranteed.
The phrasing of "$33M guaranteed in the first two years" tells you something important about PIT's offer:
the $33M wasn't guaranteed if he wasn't on the team in year 2. The actual amount of FULLY guaranteed money in the PIT offer was
only the $10M signing bonus, which is $4.5M less than Bell would have gotten under the franchise tag. However, there was also a roster bonus of another $10M payable in year 1, so if we're being realistic, unless PIT cut Bell between the signing of the contract and the start of the season he would have made
$20M in the first year.
In contrast, the amount of FULLY guaranteed money in the NYJ offer was
$28M, which is more than the $22M Todd Gurley got or the $25M David Johnson got. It's a very good haul for a free-agent RB.
Considering Bell's age and his position, the contract he signed with the Jets is definitely better than the offer from the Steelers. The only question is whether it is
better enough to justify turning down the $14.5M franchise tag, which ultimately comes down to whether or not you believe he still would have been able to get this same contract after playing 16 more games for PIT.