Man, I used to do this for a living at UBS and Lehmans in the 1990’s, so I’m a little rusty.
Unless you need the money or think the stock is going to tank, don’t base it on the most money or the least money. That simply ignores the option value. I’m using “option” to mean “call options”, which is what your “grants” are.
Options have value but are wasting assets. In other words, the value of the option decreases with time, and becomes worthless if you hit expiry without exercising or are out of the money. So, how much time does your options have to expiry? If Grant A is expiring in April 2024 and Grant C is April 2030, then you want to exercise the one that expires soon.
Given the company is a start up with big potential should it progress in the clinical trials, it does not follow a standard distribution but has a fat tail. Because your wife works there, she may have some insights (but nothing that would be insider trading) as to how well the company is run and confidence in the trials. [But she also might be smoking her own crack]. So, if you have long dated options, there is a small probability that it will have an abnormally high share price gain and that adds to the option value.
If you look at a simplified Black-Scholes derived formula. IIRC, Call option value = (Spot - strike) - carrying costs (interest rates) - dividends + Volatility Value. I assume this company does not issue dividends
Delta value is important. Grant A is deep in the money, and probably trades around a 90 Delta or tracks pretty closely to the share price. Share price goes up $1 to $26, in an efficient market at 90 delta, the call option will go up about 90 cents to be worth about $20.90. Spitballing that grant C has 50 delta, so it would only go up 50 cents or to about $5.50.
Say this a different way, if one of the clinical trials hits and the share price doubles to $50. All the grant deltas will increase but will ignore that for simplicity. Again spitballing, but Grant A should gain $25 * .9 or $22.5 of that $25 increase. It’s worth $20 now before the $25 jump in underlying stock value ($25 - $5) + $22.50 or $42.50. Grant C is worth $5 + ($25 * .5) = $17.50
Net net, grant A is practically “stock without the dividends” because it is so deep in the money. Ask yourself if you want to own this specific stock? Or would you rather sell the option and get the cash to diversify into something else or blow it on fun?
Grant C is kinda like betting on a long shot but it is worth $5 right now
Finally, I repeat that options do have value and you need to consider when they expire vs what has the biggest/lowest gain.
(I had 10 year stock grants as a signing bonus, and grants were phased out the year I joined. These came in the money at about 9 years and 9 months, and paid for my kitchen. Hindsight is wonderful, and had I converted to shares, 20+ year later would have increased about 20x vs the 3x for the house value.)